cicd: #106 Dependabot / in branch name breaking snapshot build

.github/dependabot.yml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    pull-request-branch-name:
+      # The default / breaks artifact names at archive time.
+      separator: "-"